The invention herein described relates generally to a cushioning conversion system and method and, more particularly, to improvements in the mechanisms for feeding sheet stock material into such systems for conversion into a dunnage product.
In the process of shipping an item from one location to another, protective packaging material is often placed in the shipping container to fill any voids and/or to cushion the item during the shipping process. Some commonly used protective packaging materials are plastic foam peanuts and plastic bubble pack. While these conventional plastic materials seem to perform adequately as cushioning products, they are not without disadvantages. Perhaps the most serious drawback of plastic bubble wrap and plastic foam peanuts is their effect on our environment. Quite simply, these plastic packaging materials are not biodegradable, and therefore they cannot avoid further multiplying our planet""s already critical waste disposal problems. The nonbiodegradability of these packaging materials has become increasingly important in light of many industries adopting more progressive policies in terms of environmental responsibility.
The foregoing and other disadvantages of conventional plastic packaging materials have made paper protective packaging material a popular alternative. Paper is biodegradable, recyclable and composed of a renewable resource, making it an environmentally responsible choice for conscientious shippers.
While paper in sheet form could possibly be used as a protective packaging material, i is usually preferable to convert the sheets of paper into a relatively low density pad-like cushioning or dunnage product. This conversion may be accomplished by a cushioning conversion machine, such as that disclosed in commonly assigned U.S. Pat. No. 5,123,889. The conversion machine disclosed in U. S. Pat. No. 5,123,889 converts sheet-like stock material, such as paper in multi-ply form, into relatively low density pads. Specifically, the machine converts this stock material into a continuous unconnected strip having lateral pillow-like portions separated by a thin central band. This strip is connected as by coining along its central band to form a coined strip which is cut into sections, or pads, of a desired length. The stock material preferably consists of three superimposed webs or layers of biodegradable, recyclable and reusable thirty-pound Kraft paper rolled onto a hollow cylindrical tube.
Conversion machines, like the one shown in U.S. Pat. No. 5,123,889, heretofore have used a freely rotating roll from which the stock material to be converted is fed by means of the same mechanism that advances the material through the machine. Specifically, a pair of gears that perform a connecting operation have been used to advance the material being converted. These gears stop and start their rotation during the conversion process, and this results in the need to accelerate the stock roll every time the gears start, with resulting changes in the tension of material being fed through the conversion machine. These changes in the tension of the material can affect the quality of the dunnage product being produced.
Also, when the conversion process is stopped, the rotational inertia of the stock roll can cause the stock roll to overrun and form a loose loop of material at the supply end of the conversion machine. When the conversion process is resumed, initially the material will be at a relatively low tension until the loose loop of material is taken up, at which point the tension on the paper will rapidly increase, almost instantaneously, to a relatively high level until the stock roll accelerates to match the feed rate through the machine. This quick change in tension can cause the material to tear, as well as degrade the quality of the dunnage product being produced.
Heretofore, a dancer (damper) roller has been used as a simple means to dampen the effects of starting and stopping the stock material feed mechanism and thereby attempt to maintain a more uniform tension on the stock material. In one arrangement, a dancer roller is mounted between a pair of pivot arms pivotally attached to stock roll support structure mounted to the rear end of the conversion machine""s frame. Although beneficial, proper functioning of the dancer roller is sensitive to the orientation of the machine. Conversion machines like the one shown in U.S. Pat. No. 5,123,889 have been mounted to stands for rotation about a horizontal axis generally from a vertical orientation to a horizontal orientation or beyond horizontal orientation. The dancer roller may function as desired when the machine is oriented horizontally, but not when the machine is oriented vertically. This presents a problem in that tension control cannot be readily obtained by the use of a damper roller or the like while accommodating different machine orientations ranging from vertical to horizontal and beyond.
The present invention provides a cushioning conversion system and method wherein a dancer roller is uniquely employed to eliminate one or more problems associated with prior art conversion systems and methods. The system advantageously uses the dancer roller to help maintain a greater uniformity of tension on the sheet material being fed through conversion assemblies of a cushioning conversion machine from changes in loads acting on the sheet material upstream of the dancer roller, regardless of the orientation of the conversion machine. That is, the invention enables tension control while permitting the angular orientation of the conversion machine to be varied as from a vertical orientation to a horizontal orientation, and preferably through a range of at least 90 degrees and more preferably through a range of at least or about 135 degrees. One or more features of the invention may also be used advantageously in systems which do not provide for angular adjustment of the conversion machine.
According to a particular aspect of the invention, a cushioning conversion system and method for converting sheet stock material into a relatively low density cushioning dunnage product comprise the use of a cushioning conversion machine including conversion assemblies which convert the sheet material into the cushioning dunnage product and a stock roll cart for supporting a supply of sheet stock material. The stock roll cart includes a dancer roller assembly for helping to maintain a greater uniformity of tension on the sheet material being fed through the conversion assemblies. In the preferred embodiment, the functioning of the dancer roller as a damping device is independent of the orientation of the conversion machine within a wide range preferably extending form vertical to horizontal, and beyond.
According to one specific embodiment of the invention, the stock roll cart (forming a part of the system and used to carry out the method of the invention) preferably includes a loop roller and the dancer roller assembly includes a cooperating dancer roller mounted at a distal end of a pivot arm for moving the dancer roller through a range of rotational movement. In another specific embodiment, the dancer roller assembly includes a dancer roller cooperating with a loop roller, and a guideway for linearly guiding the dancer roller through a range of linear movement. In either embodiment, there preferably is provided on the stock roll cart a low level detector which detects a low level condition of the supply of sheet stock material. In response to detection of a low level condition by the low level detector, an indicator provides an audible or visible notification of the low level condition.
As is particularly preferred, the sheet stock material, which preferably is supplied in roll form, is biodegradable, recyclable, and composed of a renewable resource.
The system also preferably includes a stand for holding the cushioning conversion machine at an elevated position. A preferred form of stand includes vertical supports to which the machine is mounted and base portions adjacent bottom ends of the vertical supports, each base portion extending in a substantially horizontal plane parallel to another base portion. Ideally, the cart is adapted to be received in a delivery position between the base portions of the stand.
The stand also preferably is configured to provide for adjustment of the angular orientation of the machine, preferably at least between a horizontal position and a vertical position, if not through a greater range of angular adjustment.
The present invention provides the foregoing and other features hereinafter fully described and particularly pointed out in the claims, the following description and annexed drawings setting forth in detail a certain illustrative embodiment of the invention, this embodiment being indicative, however, of but one of the various ways in which the principles of the invention may be employed.